I came across this page written by Blake Ross (Mozilla Firebird originator) on "marketing Mozilla Firebird (Marketing Firebird)":http://www.blakeross.com/firebird/marketing.html. It encourages Firebird users and advocates alike to promote Firebird via word of mouth (like the way Kazaa has grown), and through active promotion on your website.
Linking to the official "Why You Should Switch to the Mozilla Firebird browser":http://www.mozilla.org/products/firebird/why/ page is one way. Saying things like "Stop popup ads with Firebird." is better. Web developers will appreciate it's better CSS model (IE 6 for windows is a klutz with CSS). Power users will appreciate tabbed-browsing (no more Right-click -> Open in a New window).
Go on, promote Firebird if you love it. I do, and I've made 2 converts that I know of, and hopefully more from my entries here and at "Ensight":http://ensight.org/.